Researchers at a biotechnology company in New Zealand have found that some cows have a gene that allows them to produce milk that is low in saturated fats that is, in effect, equivalent to skimmed milk.

According to the BBC, which has reported the story in the UK, a cow with the gene was identified in 2001, and the team have since been able to breed calves that also poses the gene.

The original cow - called Marge - produces milk that is very low in saturated fats, and so should be high in healthier polyunsaturates and monounsaturated fats.

Milk with this composition could also be used to make butter that is naturally more spreadable.

Marge was discovered during a screening of milk compositions across New Zealand's four million cattle, carried out by biotech firm ViaLactia.

"When we found her daughters had the gene, that was the eureka moment, but the true holy grail will be to produce a sire with the gene," ViaLactia's chief scientist Russell Snell told New Zealand's Dominion Post newspaper.

Ed Komorowski, technical director for Dairy UK, told the BBC that lower-fat milk might suit the needs of some commercial dairy firms but not others.

"By having cows producing skimmed milk, if you are a dairy company that only really wants skimmed milk, then you might want to get it straight from the cow, without having to separate the [cream out of the milk] and sell on the surplus.”

He added: "The other side of that coin is that there are plenty of companies that will separate the cream to use in other products."

Mr Komorowski speculated that if, in future, whole milk could be made to contain unsaturated fats, it might draw some consumers back to buying this variety.

A typical pint of whole milk contains 3.5% saturated fat, a pint of semi-skimmed contains 1.7% and skimmed milk has 0.1% saturated fat content.